CE was set up as a virtual machine running on OpenShift Virtualization (KVM), and the eth0 is used to connect to the default internal pod network, by default.

apiVersion: kubevirt.io/v1
kind: VirtualMachine
metadata:
  name: example-vm
spec:
  template:
    spec:
      domain:
        devices:
          interfaces:
            - name: default
              masquerade: {} 
              ports: 
                - port: 80
# ...
      networks:
      - name: default
        pod: {}kind: VirtualMachine

in this scenario, we want to bring the 2nd interface to connect to an OVN-Kubernetes secondary network:
https://docs.redhat.com/en/documentation/openshift_container_platform/4.15/html/virtualization/networking#virt-connecting-vm-to-ovn-secondary-network:~:text=8.7.-,Connecting%20a%20virtual%20machine%20to%20an%20OVN%2DKubernetes%20secondary%20network,-You%20can%20connect

in our case, it will be eth1 (or SLO), which will be used to connect to RE.